The invention relates to a device for the electric measurement of a liquid level, in general.
The invention relates particularly to a device for the electric measurement of the level of a liquid contained within a container, having a conductive foil such as a temperature-dependent, externally electrically heated resistance foil immersed in the liquid and surrounded by a protective tube, the total resistance of which foil, detectable by an evaluation circuit, is dependent on the level of the liquid in the container. Alternately, capacitance foil bearing two conductors are used to form a capacitor, the conductive foil being developed in strip shape and being held within the protective tube by holding elements acting on at least one of its longitudinal edges in such a manner that both of its surfaces can be washed over by the liquid.
Containers in which a liquid level must be measured are frequently of rather irregular shape. Automobile gasoline tanks frequently have very complicated shapes in order to make optimal use of the space available and to permit the largest possible tank volume. Such container configurations frequently make it impossible for the device for the electric measurement of the liquid level to extend in a straight line down to the lowest point in the container. It is then necessary to bend the protective tube together with the conductive foil more strongly so that it can follow the construction of the container. With previous attempts to build such liquid measurement devices, the flexibility was not sufficient in all cases.
It is an object of the invention to further develop a device of the aforementioned type in such a manner that the greatest possible radial bending in all radial directions of the protective tube with installed conductive foil is possible.